Simple on-line scheduling algorithms for all-optical broadcast-and-select networks

This paper considers all-optical broadcast networks providing a number of s lotted WDM channels for packet communications. Each network user is equippe d with one tunable transmitter and one fixed receiver, so that full connect ivity can be achieved by tuning transmitters to the different wavelengths. Tuning times are not negligible with respect to the slot time. A centralize d network controller allocates slots in a TDM/WDM frame according to (long- term) bandwidth requests issued by users. Simple on-line transparent schedu ling strategies are proposed, which accommodate bandwidth requests when the y are received (on-line approach), with the constraint of not affecting exi sting allocations when a new request is served (transparency). Strategies t hat attempt to allocate in contiguous slots all the transmissions of each s ource on one wavelength reduce overheads, are simple, and provide good perf ormance. Even better performance can be achieved, at the cost of a modest c omplexity increase, when the transparency constraint is not strictly impose d, i.e., when a full re-allocation of existing connections is performed onc e in a while.